<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<!--step 1-->
<video width="320" height="240" controls="controls" autoplay="autoplay" id="video-local"></video>
<!--step 3-->
<video width="320" height="240" controls="controls" autoplay="autoplay" id="video-remote"></video>

<div class="buttons">
    <button id="btn-call">呼叫</button>
</div>
<script src="main.js"></script>
</body>
</html>